Factors affecting the pork meat quality

The role of the producers is particularly important to achieve high quality meat since many there are many production segments until the slaughter phase that can lead to quality deviations.

Quality deviations linked to the characteristics of appearance are the following:

• PSE (Pale,Soft,Exudative)

PSE appearance is due to the rapid glycolysis of the muscles – before and after the slaughter – resulting to the high concentration of  lactic acid  causing the rapid decline of  pH in the muscle tissue (pH drop < 5,5 in the first 45 minutes after the slaughter). The high temperature of the carcass combined with the low pH lead to protein denaturation and poor water holding capacity; these factors are responsible for the pale, soft and exudative appearance of the meat.

• DFD (Dark, Firm, Dry)

DFD meat is mainly due to the depletion of  glycogen reserves which may occur as a result either of long term fasting or intense stress which may be due to: a) mixing pigs > fighting, b) bad selection conditions, loading, transportation and unloading. In this event, the production of lactic acid is limited and the pH does not fall under 6,2. DFD meat is characterized by its dark uneven color and the short life span, elements that make it undesirable to the consumer.

Parameters as nutrition, management and the genetic material may affect the appearance and taste of the final product.

Managing practices to avoid quality deviations of DFD and PSE meat are:

• Fasting 12-18 hours before the slaughter.
• Waiting for a min of 2 hours before the slaughter.
• Sufficient space (during the waiting) -►practically, the pigs should have the possibility to lay down.
• Sprinkling water to the pigs (especially in high temperature conditions) during the time they stay at the area of the slaughter.
• Calm selection, loading, transportation and unloading of the pigs (avoidance of all possible stress factors).
• Avoiding to use the goad to guide pigs in the slaughter line.

Nutritional factors recommended to avoid PSE & DFD meat are:

Change of the fatty acids composition in the feed

The use of  fat as a source of energy is considered to be imperative in the swine feed rations in the last 15 years. The profile of the fatty acids (which are the fat) affects the organoleptic properties of the meat considerably and this is why it is so important to assess them. Practically speaking, the greater the unsaturated fatty acids contribution (vs. the saturated) in the feed, the less consistent the muscle mass/fat ratio is. This can cause considerable problems to the processing industry while, at the same time, it undermines the taste and smell of the meat due to the intense oxidation of the unsaturated fatty acids.

Vitamin Ε

Oxidation of the fatty acids is – as mentioned earlier- the main cause for pork meat spoilage.  Vitamin E is fundamental in the reduction of oxidation and, as a consequence, to both the quality and increase of the life span of the meat. It results from a plethora of scientific research, that the proper levels of Vitamin E in the feed have reduced the oxidosis of the fatty acids and improved both the color and the water holding capacity of the meat.

Addition of organic selenium

Organic selenium also functions as a natural antioxidant of fatty acids in the feed. Many studies have shown how important the interaction between selenium and Vitamin E is; organic selenium can substitute for some of the roles of  Vitamin E in the normal function of the organism.

Addition of Magnesium

Magnesium (in the form of MgO) when administered in the final phase of swine fattening reduces considerably PSE meat and at the same time it improves both the water holding capacity and the color of the meat. The action of the Magnesium focuses on the fact that it reduces stress in the pigs either a) by reducing the concentration of catecholamines in blood plasma and, to an extent, by blocking the glycogen degradation in the muscles, or b) by acting competitively with the calcium in the muscles, making them “soft”.

The selection of the proper genetic material is an important factor in the effort to produce high quality meat.  In any event, swine races with high rates of intramuscular fat and free from the halothane gene contribute to the improved pork meat quality.

SOURCES

• Pork Checkoff. National Pork Board. American Meat Science Association, # 04422, 02/2004. Authors: Dr. Michael Ellis. Univer­sity of Illinois, Dr. Floyd McKein, University of Illinois.
• MEAT lnternational.com. Understanding meat maturation, 27/02/2008.
• FEEDINFO News Services, Pork Quality After Nutrient Supplementation, 18/05/2007.
• Premier Nutrition, Technical Information Bulletins: Tastier pork & Magnesium in feed, 2009.
• Σπ. Β. Ραμαντανης, Η επίδραση της μεταφοράς στην ποιότητα του χοιρείου κρέατος. Περιοδικό της Ελληνικής Κτηνιατρικής Εταιρείας 2003, 54(4):335-346.
• Polish Journal of Food and Nutrition Sciences: o Critical points in the development of pork quality 2006, Vol. 15/56, No3. o Effect of vitamin E in swine diet on animal growth performance and meat quality parameters 2007, Vol. 57. No 1. o Proteins of meat as a potential indicator of its quality 2007, Vol. 57, No 1.
• J. Planchard, J.P. Chadwick, C.C. Warkup, M. Ellis, G.A. Deans, The influence of rate of lean and fat tissue development on pork eating quality, British Society Of Animal Science, Winter meeting 1995.
• Kurt. R.E. Klont, Effects of pH and temperature decline curves on pork quality determined under different commercial chilling conditions.
• Andy Robinson, What producers can do to improve meat quality. Centre for Genetic Improvement of Livestock, University of Guelph, Ontario – London Swine Conference, 5-6 April 2006.

Dr Rogerio G.T. da Cunha, Understanding meat maturation, Meat International, Vol.18 No2, 2008.